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    <title>Document</title>
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    <script>
      function FeiBo(n) {
        // 出口
        if (n == 1 || n == 2) {
          return 1;
        }
        return FeiBo(n - 1) + FeiBo(n - 2);
      }

      console.log(FeiBo(10));
      console.log(FeiBo(11));
      console.log(FeiBo(12));
    </script>
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